diff --git a/Scripts/postinstall b/Scripts/postinstall
index 2aee71a..8ef5fba 100755
--- a/Scripts/postinstall
+++ b/Scripts/postinstall
@@ -4,6 +4,8 @@ set -e
 
 identifier="com.ninxsoft.mist.helper"
 
-launchctl bootstrap system "/Library/LaunchDaemons/$identifier.plist"
+if ! launchctl print "system/$identifier" &> /dev/null ; then
+  launchctl bootstrap system "/Library/LaunchDaemons/$identifier.plist"
+fi
 
 exit 0
diff --git a/Scripts/preinstall b/Scripts/preinstall
index 859659f..9e23b68 100755
--- a/Scripts/preinstall
+++ b/Scripts/preinstall
@@ -2,9 +2,9 @@
 
 set -e
 
-identifier="system/com.ninxsoft.mist.helper"
+identifier="com.ninxsoft.mist.helper"
 
-if launchtl print "system/$identifier" ; then
+if launchctl print "system/$identifier" &> /dev/null ; then
   launchctl bootout "system/$identifier"
 fi